Method and device for controlling the drivetrain of a motor vehicle during gearshift operations

ABSTRACT

A coordinated control of a drive train during a gear shift is described. The core of the control lies in establishing an optimal system trajectory for the states of the internal combustion engine and the clutch for the shift operation and in supplying this trajectory to a subordinate control and regulation. Here, the determination of the optimal system trajectory occurs as a function of the stipulations of a higher-order system for controlling the drive train. In particular, it is provided for the optimal system trajectory to be adapted to the driving situation, the driver type, the operating conditions of the assemblies, and the state of the assemblies themselves. Here, the determination of the optimal system trajectory occurs via a real-time optimization algorithm that is executed during driving operation. In this manner, optimal shift operation is attained under all operating conditions that unites a high degree of comfort with a low loss of traction.

BACKGROUND INFORMATION

[0001] The invention relates to a method and device for controlling the drive train of a motor vehicle during gear shift operations having the features of the independent claims.

[0002] In vehicles having an automated gear box and an electronically actuated clutch, an automated gear change occurs by triggering the internal combustion engine, clutch, and transmission components. Here, these components must be actuated appropriately such that the gear change occurs as quickly and therefore as comfortably as possible.

[0003] The related art describes methods for determining the target transmission gear which, besides the direct input variables, also take into account the driving situation, the driver type, and operating conditions when determining the gear. For these methods, reference is made, for example, to German Patent Application 196 25 935 or German Patent Application 197 03 863.

[0004] Moreover, systems for coordinated drive train control are known. German Patent Application 199 37 455 A describes a system for controlling the assemblies in gear shift operations that is embedded in a system for controlling the drive train.

[0005] However, the known methods do not guarantee an optimal control of the shift operation with regard to traction and comfort while taking into account the driving situation, driver type, and operating conditions.

[0006] The object of the present invention is the optimal control of the assemblies of the drive train during gear shift operations with regard to traction and comfort under all operating conditions.

[0007] This object is achieved by the features of the independent claims.

ADVANTAGES OF THE INVENTION

[0008] As mentioned, the present invention relates to the coordinated control of the elements servo clutch, vehicle engine, and transmission arranged in the drive train of a motor vehicle during a change in the gear ratio. The core of the invention lies in the fact that temporal progressions of the states of the vehicle engine and the servo clutch are established for the change in gear ratio. The control of the servo clutch and the vehicle engine during the change in gear ratio then occurs in such a way that the servo clutch and the vehicle engine assume the states according to the established temporal progressions.

[0009] Thus, according to the present invention, an optimal system trajectory for the shift operation is determined for the conditions of the internal combustion engine and the clutch and this trajectory is supplied to a subordinate control and regulation. The determination of the optimal system trajectory occurs in this connection as a function of the stipulations of a higher-order system for controlling the drive train.

[0010] In a particularly advantageous embodiment of the present invention provision is made that, during driving operation of the vehicle, at least

[0011] one driver type value representative of the behavior of the driver of the vehicle and/or

[0012] one driving situation value representative of the instantaneous driving situation and/or

[0013] one operating state value representative of the operating state of at least one element of the drive train and/or

[0014] one operating condition value representative of at least one operating condition of at least one element of the drive train

[0015] is calculated. The temporal progressions are then determined dependent upon at least one of the calculated values. Thus, it is also provided according to the present invention for the optimal system trajectory to be adapted to the driving situation, driver type, operating conditions of the assemblies and the state of the assemblies themselves.

[0016] Here, the determination of the optimal system trajectory occurs via a real-time optimization algorithm that is executed during driving operation. This means that the temporal progressions are calculated and updated during driving operation. At the beginning of a change in the gear ratio, the respective updated progressions are then established as the progressions according to which the control of the servo clutch and of the vehicle engine occurs during the change in the gear ratio.

[0017] In particular, the result of this algorithm is the target progression of the engine speed and the target progression of the clutch output torque. This means that the output speed of the vehicle engine is set as the state of the vehicle engine and the output torque of the servo clutch is set as the state of the servo clutch.

[0018] Using the present invention, optimal shift operation is attained under all operating conditions that unites a high degree of comfort with a low loss of traction.

[0019] Further advantageous embodiments can be found in the dependent claims.

DRAWING

[0020]FIG. 1 shows the invention in a top-view block diagram while

[0021]FIG. 2 shows the embedding of the invention in a system for controlling the drive train. FIG. 3 shows details of the shifting coordination. FIGS. 4a and 4 b as well as 5 a and 5 b provide examples of the calculation according to the present invention of the temporal progressions.

EXEMPLARY EMBODIMENT

[0022] The invention shall be described in the following using exemplary embodiments.

[0023] Using a drive train control, in a vehicle with an automated gear box (AGB) and electronically actuated clutch, the change of gears occurs via coordinated control 111 of the components engine, clutch, and transmission. FIG. 1 shows the system architecture of the drive train control.

[0024] The driving torque desired by the driver is calculated by drive train control 111 as a function of relative position hfp of accelerator 110 and transmission output speed n_ga proportional to the vehicle speed. Output engine torque md_ma_soll or the setting of an engine speed n_m_soll is requested by engine control 101 a. Clutch control 103 a is requested to adjust the clutch in such a way that it is able to transfer a torque md_ka_soll. Alternatively, it is also possible for the stipulation of a target position or target force of the actuator that actuates automated clutch 103 to be provided.

[0025] Transmission control device 105 a is requested by coordinator 111 to set target transmission gear g_soll.

[0026] Using appropriate sensors 102, 104, and 106, engine speed n_m, transmission input speed n_ge, and transmission output speed n_ga are determined and provided to drive train control 111. Moreover, control components 101 a, 103 a, and 105 a provide further signals to drive train control 111 that will be clarified in conjunction with the functional structure of the drive train control.

[0027]FIG. 2 shows the embedding of the invention in a system for controlling the drive train. As a function of the position of accelerator hpf and transmission output speed n_ga proportional to the vehicle speed, vehicle coordinator 201 determines target drive power md_an_soll. This target drive performance is converted by drive coordinator 202 by triggering the assemblies engine 101, clutch 102, and transmission 105. For this purpose, it provides target engine output torque md_ma_soll and target engine speed n_m_soll to engine control 203. Drive coordinator 202 also provides torque md_ka_soil to clutch control 204, which clutch 102 should be able to transmit. Target gear g_soll is specified by transmission control 205.

[0028] A driver (engine driver 2021, clutch driver 2022, transmission driver 2023) is assigned to each of assemblies 101, 102, and 103 within drive coordinator 202. The coordinated actuation of assemblies 101, 102, and 103 during gear shift operations is performed by shift manager 2024, which is part of drive coordinator 202 and provides target variables to drivers 2021, 2022, and 2023 during shifting. Shift manager 2024 requests a target clutch input torque md_ke_soll and/or a target engine speed n_m_soll from engine driver 2021. Shift manager 2024 also requests the setting of a clutch torque md_ka_soll from clutch driver 2022 and is able to request a shifting prohibition from transmission driver 2023.

[0029] Within shift manager 2024, an engine/clutch regulator 20244 ensures coordinated control and regulation of engine 101 and clutch 102. It receives the target progression of engine speed n_m_ref from a target trajectory block for engine speed 20242. It also receives the target progression of clutch output torque md_ka_ref from a target trajectory block for clutch output torque 20243. A shifting coordinator block 20241 is responsible for the coordination of the specifications.

[0030] Based on a block diagram, FIG. 3 shows the method for determining target trajectories 20242 and 20243 for the clutch output torque and the engine speed that is attained within the arithmetic block for shifting coordinator 20241.

[0031] In order to calculate the target trajectory for clutch output torque md_ka_ref, information is provided to block 320 (optimization of target trajectory parameter) about the driver type, driving situation, and operating conditions as well as the shifting type and the desired target value for the clutch output torque at the end of shifting phase md_ka_ziel. The shifting type provides coded information regarding the shifting, for example, 1-2 pull shift (changing from first gear to second gear while the engine is driving the vehicle), 4-3 push shift (changing from fourth gear to third gear while the vehicle is driving the engine). These input variables are provided to block 320 by shifting coordinator 20241 and/or by drive coordinator 202. The calculation of values that the driver type (e.g., “sporty” or “economy”), the driving situation (e.g., mountain driving, winter driving), and the operating conditions of the assemblies (e.g., temperature of the engine and/or clutch) can be calculated in a manner that is known per se.

[0032] In block 320, parameter vector sigma_k, which establishes the characteristics of target trajectory md_ka_ref, is determined from this information. In particular, the elements of vector sigma_k describe the shape of target trajectory md_ka_ref (e.g., linear, PT1-shaped, sinusoid) and its duration (and thus the time interval {ta, te}). The mapping of the input information from block 320 on parameter vector sigma_k may occur via algebraic calculation specifications, characteristic curves, characteristic maps, fuzzy rules, or neuronal networks, optionally also based on a model description of the drive assemblies and the vehicle.

[0033] In block 321 (calculation of target trajectory), target trajectory md_ka_ref is calculated. The output of block 321 is a depiction of the target trajectory as a characteristic curve over time interval {ta, te}. In addition to parameter vector sigma_k, the initial value of clutch output torque md_ka_start and the desired target value for clutch output torque md_ka_ziel at the end of the shift phase are input variables of block 321.

[0034] In order to calculate the target trajectory for engine speed n_m_ref, information is provided to block 325 (optimization of target trajectory parameter) regarding the driver type, driving situation, and operating conditions. Using this information, it determines a parameter vector sigma_m that establishes the characteristics of target trajectory n_m_ref. The elements of vector sigma m in particular describe the shape of target trajectory n_m_ref (e.g., linear, PT1-shaped, sinusoid). The mapping of the input information of block 325 on parameter vector sigma_m may occur via algebraic calculation specifications, characteristic curves, characteristic maps, fuzzy rules, or neuronal networks, optionally also based on a model description of the drive assemblies and the vehicle.

[0035] In block 326 (calculation of target trajectory), target trajectory n_m_ref is calculated. The output of block 326 is a depiction of the target trajectory as a characteristic curve over time interval {ta, te}. In addition to parameter vector sigma_m, the initial value of engine speed n_m_start, the gradient of engine speed d/dt(n_m_start), the target value of engine speed n_m_ziel and its gradient d/dt(n_m_ziel) are input variables of block 326.

[0036] The calculation of the target trajectories for the clutch output torque and/or the engine speed in arithmetic blocks 321 and 326 occurs using pre-defined mathematical functions such as, for example, a linear, exponential, or sinusoid function.

[0037] In an advantageous embodiment of the invention, spline functions are used to determine the target trajectories for the clutch output torque and/or the engine speed. For example, the description of the progression of engine speed n_m_ref is shown using spline functions in FIGS. 4a and 4 b and the description of target clutch output torque md_ka_ref is shown using spline functions in FIGS. 5a and 5 b.

[0038] In order to calculate the target trajectory for the engine speed in block 326, in a first step, the number of the spline base functions (B-splines) and their order as well as their distribution over time interval {ta, te} are established. This occurs as a function of parameter vector sigma_m. Correspondingly, in FIG. 4a, four base functions of the order 4 are shown. Using these base functions, the target progression of the engine speed is described in such a way that the initial value of engine speed n_m_start, the gradient of engine speed d/dt(n_m_start), the target value of engine speed n_m_ziel, and its gradient d/dt(n_m_ziel) are satisfied (FIG. 4b). For this purpose, a method for spline interpolation is used that is described in the literature (de Boor, C.: A Practical Guide to Splines. Applied Mathematical Sciences, Vol. 27, Springer-Verlag, New York, 1978. Chapter on spline interpolation).

[0039] In order to calculate the target trajectory for the clutch output torque in block 321, in a first step, the number of spline base functions (B-splines) and their order as well as their distribution over time interval {ta, te} are established. This occurs as a function of parameter vector sigma_k. In the example, it was defined using parameter vector sigma_k that the first 70% of the torque build-up should occur in a linear manner. Correspondingly, in FIG. 5a, 6 base functions of the order 4 are shown. Using these base functions, the target progression of the clutch output torque is described in such a way that, beginning from an initial value md_ka_start, the torque reaches target value md_ka_ziel (FIG. 5b). 

What is claimed is:
 1. A method for coordinated control of the elements servo clutch (103), vehicle engine (101), and transmission (105), arranged in the drive train of a motor vehicle during a change in the gear ratio, temporal progressions (20242, 20243) of the states of the vehicle engine (101) and the servo clutch (103) being established for the change in gear ratio, and the control of the servo clutch (103) and the vehicle engine (101) during the change in gear ratio occurring in such a way that the servo clutch (103) and the vehicle engine (101) assume the states according to the established temporal progressions (20242, 20243).
 2. The method according to claim 1, wherein the output speed (n_m) of the vehicle engine is established as the state of the vehicle engine (101) and the output torque (md_ka) of the servo clutch is established as the state of the servo clutch (103).
 3. The method according to claim 1, wherein, during driving operation of the vehicle, at least one driver type value representative of the behavior of the driver of the vehicle, and/or one driving situation value representative of the instantaneous driving situation, and/or one operating state value representative of the operating state of at least one element of the drive train and/or one operating condition value representative of at least one operating condition of at least one element of the drive train calculated and the temporal progressions are determined dependent upon at least one of the calculated values.
 4. The method according to claim 1, wherein the temporal progressions (20242, 20243) are calculated and updated during driving operation and, at the beginning of a change in the gear ratio, the respective updated progressions are established as the progressions according to which the control of the servo clutch (103) and of the vehicle engine (101) occurs during the change in the gear ratio.
 5. The method according to claim 4, wherein the temporal progressions (20242, 20243) are calculated during driving operation via a real-time optimization algorithm.
 6. A device for the coordinated control of the elements servo clutch (103), vehicle engine (101), and transmission (105), arranged in the drive train of a motor vehicle, during a change in the gear ratio, coordination means (20241) being provided, by which temporal progressions (20242, 20243) of the states of the vehicle engine (101) and the servo clutch (103) are established for the change in gear ratio, and the control of the servo clutch (103) and the vehicle engine (101) during the change in gear ratio occurring in such a way that the servo clutch (103) and the vehicle engine (101) assume the states according to the established temporal progressions (20242, 20243).
 7. The device according to claim 6, wherein the output speed (n_m) of the vehicle engine is established as the state of the vehicle engine (101) and the output torque (md_ka) of the servo clutch is established as the state of the servo clutch (103).
 8. The device according to claim 6, wherein, during driving operation of the vehicle, at least one driver type value representative of the behavior of the driver of the vehicle, and/or one driving situation value representative of the instantaneous driving situation, and/or one operating state value representative of the operating state of at least one element of the drive train, and/or one operating condition value representative of at least one operating condition of at least one element of the drive train is calculated, and the temporal progressions are determined dependent upon at least one of the calculated values.
 9. The device according to claim 6, wherein the temporal progressions (20242, 20243) are calculated and updated during driving operation and, at the beginning of a change in the gear ratio, the respective updated progressions are established as the progressions according to which the control of the servo clutch (103) and of the vehicle engine (101) occurs during the change in the gear ratio.
 10. The device according to claim 9, wherein the temporal progressions (20242, 20243) are calculated during driving operation via a real-time optimization algorithm. 